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United States Department of Agriculture

Agricultural Research Service

Title: Sugarbeet Performance with Curly Top Is Related to Virus Accumulation and Age at Infection

Authors
item Wintermantel, William
item Kaffka, Stephen - UNIV. CALIF., DAVIS

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 28, 2005
Publication Date: January 3, 2006
Citation: Wintermantel, W.M., Kaffka, S.R. 2006. Sugarbeet performance with curly top is related to virus accumulation and age at infection. Plant Disease. 90:657-662. DOI:10.1094/PD-90-0657

Interpretive Summary: Resistance to curly top disease caused by Beet curly top virus (BCTV) and related curtoviruses has been important to sustainable sugar beet (Beta vulgaris L.) production in the western United States for most of the last century. Recent advances in sugarbeet genetics have led to the development of high-yielding cultivars that produce exceptional yields, but can result in significant losses in years with early infection or abundant curly top. A greenhouse assay has been developed to rapidly test cultivars for a broad array of factors affecting performance in the presence of curly top. Previous studies have shown that sugarbeet plants were more susceptible and losses more severe when seedlings were infected by BCTV, but less severe when plants were larger at the time of infection. To evaluate more precisely the relationship between age at infection, disease severity, virus accumulation and yield loss in modern cultivars that were not bred for curly top resistance, individual sugarbeet plants varying in degree of resistance and susceptibility to curly top were inoculated with 20 viruliferous beet leafhoppers (Circulifer tenellus) each when plants had 2, 4 or 6 true leaves, and maintained in a greenhouse for 6 weeks. When plants were inoculated at the 2 leaf stage, all cultivars became severely stunted with high disease ratings and similar rates of symptom development, regardless of resistance or susceptibility of the cultivar. Plants inoculated at 4 and 6 leaf stages exhibited increasing separation between resistant and susceptible phenotypes, with highly resistant cultivars performing well with low disease ratings and increased plant weights relative to susceptible cultivars. High yielding cultivars performed only slightly better than the susceptible control cultivar. Results from greenhouse trials matched those from field trials conducted under heavy curly top pressure. Importantly, low virus concentration was directly correlated with lower disease ratings and higher plant weight, while elevated virus concentrations corresponded to higher disease ratings and lower weights. This demonstrates a rapid greenhouse assay involving multiple traits can provide a rapid and effective means of selecting cultivars with improved curly top control, and could lead to more rapid incorporation resistance into high-yielding sugarbeet.

Technical Abstract: Resistance to curly top disease caused by Beet curly top virus (BCTV) and related curtoviruses has been important to sustainable sugar beet (Beta vulgaris L.) production in the western United States for most of the last century. Recent advances in sugarbeet genetics have led to the development of high-yielding cultivars that produce exceptional yields, but can result in significant losses in years with early infection or abundant curly top. A greenhouse assay has been developed to rapidly test cultivars for a broad array of factors affecting performance in the presence of curly top. Previous studies have shown that sugarbeet plants were more susceptible and losses more severe when seedlings were infected by BCTV, but less severe when plants were larger at the time of infection. To evaluate more precisely the relationship between age at infection, disease severity, virus accumulation and yield loss in modern cultivars that were not bred for curly top resistance, individual sugarbeet plants varying in degree of resistance and susceptibility to curly top were inoculated with 20 viruliferous beet leafhoppers (Circulifer tenellus) each when plants had 2, 4 or 6 true leaves, and maintained in a greenhouse for 6 weeks. When plants were inoculated at the 2 leaf stage, all cultivars became severely stunted with high disease ratings and similar rates of symptom development, regardless of resistance or susceptibility of the cultivar. Plants inoculated at 4 and 6 leaf stages exhibited increasing separation between resistant and susceptible phenotypes, with highly resistant cultivars performing well with low disease ratings and increased plant weights relative to susceptible cultivars. High yielding cultivars performed only slightly better than the susceptible control cultivar. Results from greenhouse trials matched those from field trials conducted under heavy curly top pressure. Importantly, low virus concentration was directly correlated with lower disease ratings and higher plant weight, while elevated virus concentrations corresponded to higher disease ratings and lower weights. This demonstrates a rapid greenhouse assay involving multiple traits can provide a rapid and effective means of selecting cultivars with improved curly top control, and could lead to more rapid incorporation resistance into high-yielding sugarbeet.

Last Modified: 12/19/2014
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